US: Super Wide (XXL) / 64mm to United Kingdom Size Extra Small

US: Super Wide (XXL) / 64mm: Corresponds to a nominal width of 64 $\text{mm}$ (2.52 $\text{in}$), length of 215 $\text{mm}$ (8.46 $\text{in}$), average structural girth of 128 $\text{mm}$ (5.04 $\text{in}$), and fit category Extra Extra Large / Super Wide.

United Kingdom Size Extra Small: Corresponds to a nominal width of 45 $\text{mm}$ (1.77 $\text{in}$), length of 160 $\text{mm}$ (6.3 $\text{in}$), average structural girth of 90 $\text{mm}$ (3.54 $\text{in}$), and fit category Extra Small / Pediatric / Snug.